Does staying up late make you fat? 3. March 2009 William Davis (5) Lack of sleep makes you crabby. But can staying up late make you fat? Or diabetic? Or increase heart disease risk? Can forcing your body to ignore its evolutionarily-programmed day-night/sleep-wakefulness cycle also distort health, even when sleep is adequate?Yet another study adds to the growing clinical literature documenting the lack of sleep, or, in this case, the "violation" of circadian rhythms that occurs with unpredictable or shifting sleep patterns.In this small study of 10 men and women, forcing them to sleep on an unnatural 28-hour per "day" schedule, causing a dyssynchrony with natural day-night cycles, yielded increased glucose (blood sugar) levels, poor response to insulin, increased blood pressure. It also led to a decrease in leptin levels, a phenomenon that can trigger increased appetite. Such circadian misalignment was meant to recreate the distorted day-night cycles of shift workers, a group that is unusually prone to diabetes and heart disease. This study further confirms that there are indeed unhealthy physiologic consequences of defying normal day-night sleep cycles. This study suggests that, not only is sufficient sleep important for health, but the predictability and concordance with normal circadian cycles is also important. Add to this previous studies demonstrating an association with sleep deprivation and low HDL/high triglycerides (Kaneita Y, et al 2008) and increased likelihood of having a positive heart scan (coronary calcium) score (King CR et al 2008), and it is increasingly clear that sleep is a crucial factor for overall health. It may even be a helpful strategy to control weight. A full report on the importance of sleep is planned for the Track Your Plaque website.